title: Two mitochondrial genes under episodic positive selection in subterranean octodontoid rodents.
abstract: Tuco-tucos (Ctenomys) and related coruros (Spalacopus) are South American subterranean rodents. An energetically demanding lifestyle within the hypoxic, underground atmosphere may change the selective regime on oxidative phosphorylation. We examined whether weak and/or episodic positive directional selection affected the evolution of two mitochondrial genes (COX2, CytB), in a background of purifying selection in these lineages. We estimated rates of synonymous (dS) and non-synonymous (dN) substitutions and found: 1) significantly higher dN/dS ratio in subterranean groups relative to non-subterranean related species, and 2) two codons in each gene under episodic selection: 94 and 277 of COX2 and 269 and 307 of CytB.
authors.affiliation: Departamento de Ecología y Evolución, Facultad de Ciencias, Universidad de la República, Iguá 4225, Montevideo 11400, Uruguay. Electronic address: ivanna@fcien.edu.uy.
authors.forename: Ivanna H
authors.initials: IH
authors.lastname: Tomasco
authors.affiliation: Departamento de Ecología y Evolución, Facultad de Ciencias, Universidad de la República, Iguá 4225, Montevideo 11400, Uruguay. Electronic address: lessa@fcien.edu.uy.
authors.forename: Enrique P
authors.initials: EP
authors.lastname: Lessa
mesh_terms: D000818:Animals; D003062:Codon; D051546:Cyclooxygenase 2 / Q000235:genetics; D045303:Cytochromes b / Q000235:genetics; D019143:Evolution, Molecular; D050259:Genes, Mitochondrial; D014644:Genetic Variation; D010802:Phylogeny; D012377:Rodentia / Q000235:genetics*; D012641:Selection, Genetic
chemical_list: D003062:Codon; D045303:Cytochromes b; D051546:Cyclooxygenase 2
keywords: Adaptation; COX; COX1; COX2; COX3; CytB; Cytochrome b; Cytochrome c oxidase II; Evolution; OXPHOS; Subterranean niche; cytochrome b; cytochrome c oxidase; cytochrome c oxidase subunit I; cytochrome c oxidase subunit II; cytochrome c oxidase subunit III; dN; dN/dS; dS; mitochondrial genome; mtDNA; oxidative phosphorylation; rate of non-synonymous substitutions; rate of synonymous substitutions; ratio between rate of synonymous and non-synonymous substitutions